The options include arresting Muqtada al-Sadr, 30, whom USA officials view as a possible threat to the military coalition occupying Iraq. However, the Americans also want to avoid touching off rioting or other violence by moving against the cleric, the officials said.

“Our problem with Sadr … is that anybody that incites violence against the coalition, that’s not proper or legal,” Joint Chiefs of Staff Chairman Gen. Richard Myers said at the Pentagon. “Anyone who does that will be subject to some sort of action.”

The cleric exhorts his followers with fiery anti-American sermons but so far has stopped short of calling directly for attacks on USA military forces. His militia openly defies the USA-led administration’s bans on private armies and people carrying unlicensed guns. His followers have engaged in deadly shootouts with other Shia groups and American troops in the past two weeks, most recently in Karbala on Tuesday.

USA officials believe al-Sadr’s actions require a response, said a senior Defense official who spoke on condition of anonymity, and what that response will be will be determined in the next few days. The official suggested other Shia groups or Iraqi security forces might deal with al-Sadr on their own.

Such unusually strong comments from Pentagon officials could suggest some imminent USA-backed move, or perhaps an attempt to get al-Sadr to back down without a fight.

Moving against al-Sadr could spark unrest among his followers, but USA military and coalition officials are finding it harder to ignore al-Sadr’s increasingly open challenges to the American occupation and to Iraqis who cooperate with it.